U.S. Pat. No. 4,758,970, filed Aug. 8, 1984, and issued to Emco Wheaton, Inc. discloses a marine loading arm as an articulated device used to on-load or off-load fluids between a vessel and a loading region such as a dock, wharf or pier. Such devices are particularly useful in the petroleum transportation industry for which tremendous volumes of fluid must be transferred safely between the moored area and the dock. A marine loading arm typically includes a vertical mounting structure supporting a fulcrum about which a primary arm pivots. A secondary arm is pivotally linked to the primary arm and a counter weight is attached to the opposite end of the primary arm to balance the same about the fulcrum. The secondary arm has an end flange attached thereto which is coupled to a flange support on the vessel manifold to access the fluid. Three dimensional movement of the articulated arm, and, thus the end flange, is accomplished by pivotal movement of the primary arm about the fulcrum and the secondary arm pivoting with respect to the primary arm. Also the fulcrum is carried on an upper portion of the mounting structure which is rotably coupled to a lower portion of the mounting structure by a swing joint, thus allowing the articulated primary and secondary arms to move about the longitudinal axis of the mounting structure. Such a loading arm device can be controlled by hydraulic actuators of the piston cylinder type which pivot the articulated arm so as to position the end flange at a desired coupling location.
The '970 patent further discloses an apparatus for monitoring the spatial position of a reference point relative to a predetermined origin, the reference point being located on an articulated marine loading arm having a plurality of pivotally interconnected fluid conduits forming pivot angles at the interconnections of the conduits. The apparatus includes segments subtended by the pivot angles with means for sensing the length of the segments as the loading arm articulates. The dispensing means generates electrical signals proportional to segment lengths and a computer receives the electrical signals and calculates the position of the reference point based on the known geometry of the loading dock.
U.S. Pat. No. 6,938,643, filed Jul. 31, 2003, and issued to Single Buoy Moorings, Inc., discloses a storage structure having a fluid transfer boom for transfer of cryogenic liquids such as liquid natural gas from a first storage structure to a vessel. The boom has two arms which are rotably connected at their ends via a swivel joint. A liquefied natural gas duct is supported within the first and second arms which form a gas tight housing around the liquefied natural gas duct. The transfer boom provides a redundant containment system wherein the liquid natural gas (LNG) duct is supported by the structurally strong and self-supporting transfer boom which contains the natural gas in case of a leak in the inner (LNG) duct. The transfer boom can have 7 swivel joints in total such that rotation in all directions is possible when the vessel is moored to the storage structure and has to cope with relative motions of yaw, pitch, roll, heave, sway and surge. The storage structure may for instance be an off shore storage buoy for liquefied natural gas which is anchored to the sea bed by means of anchor lines. The storage structure can be a weather waning vessel.
International Patent Publication WO 2007/120039, filed Feb. 28, 2007 discloses a vessel with a motion compensation platform. The platform is provided with at least one carrier for bearing, moving or transferring a load. Actuators for moving the carrier relative to the vessel preferably in six degrees of freedom are coupled to the platform. A control system for driving the actuators is coupled to the actuators. Motion sensors which measure the motion of the vessel relative to at least one element in the surrounding area are pro-vided. The measurements are used as input the for the control system.